During the past year we completed in vitro laboratory studies documenting a clear advantage to monocytes-derived dendritic cells prepared using a shortened (3-day) differentiation period in lieu of the standard 7 day differentiation interval used previously at the NIH in preparing clinical grade dendritic cells for human ressearch protocols. Specifically, "3-day DCs" expressed higher and more reproducible levels of relevant surface molecules such as CCR7 and produced greater amounts of IL 12 than 7-day DCs. If monocytes-derived DCs behave similarly in vivo, based on the current understanding of dendritic cell physiology, the "3-day" DCs would be expected to traffic and present antigens to T cells more effectively than the "7-day" DCs used previously. These findings have been published and the protocols used by the Department of Transfusion Medicine (DTM) for dendritic cell preparation have been altered reflect these findings. Institute investigators (Drs. Mackall, Berzofsky and Wayne) in collaboration with DTM are currently enrolling patients in 3 clinical protocols to treat acute lymphoblastic leukemia, childhood sarcomas, and other solid tumors using the "3-day" methodology described above.